This study is proposed as a proof of principle: that gene delivery to the central nervous system can mitigate the harmful effects of HIV and HIV gene products on the brain. HIV encephalopathy is a potentially devastating complication of AIDS. There is no current therapy for CNS HIV infection: conventional antiretroviral drugs penetrate the brain poorly and anti-HIV CNS gene therapy has not been reported. Transgenes are currently available that are highly potent inhibitors of HIV entry and replication. Further, HIV envelope glycoprotein, gp120, has been implicated in neuron cell death via oxidant-related mechanisms in HIV encephalopathy. We have confirmed that gp120 causes apoptosis in human neurons, and that providing these cells with antioxidant enzymes, such as catalase protects them from apoptosis induced by HIV proteins. We submit that tools are now available to test gene delivery for the first time to address this problem, and propose to use gene delivery techniques to test the following hypothesis - Anti-oxidant and anti-HIV transgenes can protect cns cells from HIV and neural apoptosis caused by HIV gene products. To test this hypothesis, we will use as tools gene delivery vehicles derived from Tag-deleted SV40 (rSV40s). These vectors efficiently transduce key CNS cell targets for HIV and neurotoxicity induced by HIV, i.e., microglia, neurons, and monocyte-derived macrophages (MDM). We propose 4 aims: 1. Identify longitudinally optimal transgenes individually and in combination to inhibit HIV in CNS cells 2. Assess CNS and peripheral routes of administration to deliver rSV40s to the brain most effectively 3. Measure the ability of anti-CCR5 genes delivered in vivo to reduce MDM and microglial CCR5 gene delivery in vitro and in vivo to apoptosis-induced products. Despite the frequency and severity of CNS HIV infection, people with HIV encephalopathy have few treatment options. We propose to address this therapeutic challenge using gene delivery to the CNS, both to protect the brain from HIV infection and to mitigate HIV-induced CNS dysfunction.